$f(R)$ Gravity and Crossing the Phantom Divide Barrier

TL;DR

This paper investigates $f(R)$ gravity models in the Einstein frame, focusing on their phantom behavior and comparing it with traditional phantom scalar fields to understand their cosmological implications.

Contribution

It provides a detailed analysis of phantom crossing in $f(R)$ models within the Einstein frame, highlighting differences from standard phantom scalar field models.

Findings

$f(R)$ models can exhibit phantom behavior in the Einstein frame.

Comparison shows differences between $f(R)$ gravity and canonical phantom scalar fields.

Insights into the cosmological viability of $f(R)$ models with phantom crossing.

Abstract

The $f(R)$ gravity models formulated in Einstein conformal frame are equivalent to Einstein gravity together with a minimally coupled scalar field. We shall explore phantom behavior of $f(R)$ models in this frame and compare the results with those of the usual notion of phantom scalar field.